The gene for the male-enhanced antigen, MEA, was isolated with an antiserum against the H-Y antigen, or serologically detected male (SDM) antigen, from a prokaryotic expression cDNA library of the mouse testis. Molecular analyses revealed that MEA shares considerable similar characteristics attributed to the serological H-Y antigen, and is considered as a candidate gene for the latter. The MEA is genetically conserved and shows a male-enhanced expression in established male cell lines, Sertoli cells, 14-day mouse embryo, and premature and mature mammalian testes. Two other genes, Gene A and B, are linked to the MEA gene in both human and mouse genomes, and express similarly as MEA. This gene cluster is located in human chromosome 6 and mouse chromosome 17. The genetic conservation and male-enhanced expression suggest that the products from MEA gene cluster are important factors in mammalian spermatogenesis and/or testis- determination. Our long term goals are to define the functions and the mechanisms of biological actions to the MEA gene cluster. We plan to isolate both full-length cDNA and genomic sequences for this gene cluster, and determine their DNA sequences, deduced proteins, and promoter structures. We will study the molecular regulation of their expression by identifying their tissue-specific promoters, cis-acting enhancers, trans-acting regulatory factors, and the chromatin alteration associated with their transcriptional activity at different spermatogenic stages. We will synthesize the MEA by genetic engineering methods and raise mono-specific antibodies against these proteins. We plan to use these antibodies to isolate the native molecules and to study the tissue-specific expression during mouse fetal development. We are particularly interested in identifying the cell types expressing these genes during gonadogenesis. We will further examine their possible roles in testis organization using in vitro gonadal cell dissociation- reassociation assays in the presence or absence of purified MEA and related proteins. Transgenic mice will be constructed to harbor inducible MEA genes whose expression can be modulated with external stimulants. Result from the proposed studies will provide valuable information concerning the mechanisms of sexual dysfunctions and spermatogenic failure in mammals, and can be related to clinical manifestations in man.